Closed circuit hydraulic system for drawing tubes, pipes, rods, bars and the like



0 1 6 m 7 e 7 h 8 S 3 2 t e G m N S mmz A K RI D L March 1966 A. A. PINARD CLOSED CIRCUIT HYDRAULIC SYSTEM FOR TUBES, PIPES, RODS, BARS AND THE Filed April 19, 1963 A. A. P ARD 3,238,760 D CIRCUIT HYDRAU c SYSTEM FOR DRAWING BBS, PIPES, RODS, BARS AND THE LIKE 2 Sheets-Sheet 2 ww m w G 9 6 l e 1 l n 8 m. h A C d r a u 1 M F United States Patent 3,238,760 CLOSED CIRCUIT HYDRAULIC SYSTEM FOR DRAWING TUBES, PIPES, RODS, BARS AND THE LIKE Albert A. Pinard, Corso XXII Marzo 4, Milan, Italy Filed Apr. 19, 1963, Ser. No. 274,289 Claims priority, application Italy, Feb. 16, 1963, 3,329 8 Claims. (Cl. 7229tl) The present invention relates to the cold or hot drawing of tubes, pipes, rods, bars and the like.

The conventional benches for cold drawing ferrous and non-ferrous metal tubes and other sections are operated by mechanical energy transmitted by a speed reducer and a single central chain or two lateral chains. The chains extend to the drawing carriage, running along the drawing part of the drawing bench, from an electric motor. The electric motor may be fed by direct current. A Ward-Leonard unit may be used. A first drawback of the mechanical system consists of the necessity to rectify the alternating current power supply to direct current. The Ward-Leonard unit and speed reducer are heavy, complicated and expensive devices, consequently representing a further important drawback of the system. The electric motor with its Ward-Leonard unit, the further electric equipment and the speed reducer require much space, which space is important in the factory, so that this is another drawback. In the case of a single central drawing chain, usually adopted, the drawn tubes or bars have to be discharged from the drawing bench by means of particular, horizontally oscillating arms, each one comprising a special driving element.

Still another important drawback is in the heavy wear to which the single central or the lateral chains are submitted in use, and to the fact that the drawing carriage, although guided along its running track, moves under continuous transverse vibrations. This causes irregular handling of the tubes or bars to be drawn, and consequently presents another disadvantage of the mechanical drawing system. Still a further drawback of the mechanical drawing of tubes and bars is the impossibility of providing for the physical and chemical properties of the raw material or metal alloy of which said tubes or bars to be drawn are made, so that the final products may be undesirable.

Not only the above mentioned drawbacks but still further ones have to be considered, as for example the heavy, complicated and expensive maintenance of mechanically driven draw benches, etc.

The purpose of the present invention therefore is to avoid all these drawbacks and disadvantages.

An object of the invention is to provide a new method of cold drawing for tubes and bars of ferrous and nonferrous metal or metal alloys. The new method of the invention comprises a more flexible processing of the material to be drawn, achieved by the application of hydraulic energy.

Another object of the invention is to apply the hydraulic energy to the drawing carriage itself rather than to the pistons. This provides the same advantageous effects as obtained on mechanical drawing benches wherein the drawing carriage is trailed by chains.

Another object of the invention is to realize a closed hydraulic circuit of the high pressure hydraulic fluid for the operation of the drawing bench. The hydraulic circuit comprises a fluid tank, a pumping unit, hollow pistons, a high pressure chamber within the drawing carriage, and back to the fluid tank.

Still another object of the invention is to produce very long tubes, pipes, rods, bars or the like of every kind of ferrous and non-ferrous metal or metal alloys (for example, 130 feet long and longer) by using a combination "ice of heavy, high pressure hydraulic system components of the required sizes, joined together with great rigidity and packing against losses of the high pressure fluid in the system. These components cooperate with long pistons made of surface hardened, treated and accurately polished steel and the pistons are hollow, as stated, for the circulation of the hydraulic driving fluid therethrough under high pressure.

A further object of the invention is to permit the pistons to move without bending or twisting stresses. This is achieved by supporting the pistons in the hydraulic cylinders by a plurality of supporting and sliding piston rings accordingly shaped, fastened and distanced from each other. The pistons are preferably made of a special aluminum bronze, for example, of so called AMPCO metal. Outside of the cylinders, the pistons are supported along their drawing stroke by accordingly shaped ball bearing-mounted support rollers.

A further object of the invention is to provide absolute rectilinear movement of the drawing carriage by rig-idly and strongly connecting, such as by welding, the free ends of both the lateral pistons with the drawing carriage. This results in a strong drawing unit which moves without any transverse vibrations and also provides the fluid connection between both pistons through the high pressure chamber within the drawing carriage for the attainment of the aforementioned closed hydraulic circuit of high pressure hydraulic fluid.

Another object of the invention is to provide the high pressure hydraulic fluid circuit with the necessary valves, hydraulic distributors, electric relays, switches, etc. for the synchronization of all movements of the hydraulically operated drawing bench of the invention, and with speedometer, pressure gauges, and electric meters for the safe and convenient operation of the complete drawing plant.

Still a further object of the invention is to provide a means for facilitating the starting of the drawing operation. A suitable means is a high pressure intensifier or multiplier, which, after initiating the drawing operation is automatically replaced bythe operation of the drawing apparatus at its normal pressure operation.

A further object of the invention is to provide the high pressure hydraulic fluid circuit with means for preventing ram shocks, usually occurring in high pressure hydraulic systems. This may be achieved, for example, by a shock damper, suitably positioned in the highest position of the plant.

Another object of the invention is to provide a compact system by locating all plant composing devices and accessories, electrical and hydraulic or pneumatic, such as, for example, the fluid tank, pipes, pumping units and the like, within the boundaries of the drawing bench, without using any further space.

Another object of the invention is to provide a carriage return system for the drawing carriage and both lateral pistons in one unit to return them to their starting position. This may be achieved by a pair of ropes attached to books on both lateral sides of the drawing carriage. The ropes may be trailed by an electric winch located beneath the forebench, just behind the die-holder.

Still another object of the invention is to control the exhaust valves of the hydraulic cylinders and the return movement of the drawing carriage and pistons after the conclusion of the drawing stroke, when the tubes or bars to be drawn have been removed from their respective dies. The control may be achieved by a photocell positioned at the level of the horizontal axis of each die. A light ray traverses the front part of each die and is not interrupted by the tube, bar or pipe of the corresponding die reaching the termination of its drawing stroke, and being removed from said corresponding die. The light ray is received by the photocell and the photocell first controls the exhaust valves of the hydraulic cylinders and immediately thereafter starts the electric motor which operates the return winch to return the drawing carriage and pistons to their start positions so that they are ready for the next drawing cycle.

The automatic hydraulic system of the invention also comprises a plurality of additional components. These are as follows: The drawing carriage is provided with an independent but synchronisable controlled hydraulic or pneumatic system for controlling the operation of the grippers for gripping the tube or bar ends projecting from the respective dies. The rotating feeding drum, which receives at its upper part from the supply of raw material the tubes or bars to be drawn, and rotates 180 to permit the feeding of the tubes or bars to the dies, comprises two diflerent hydraulic or pneumatic systems. The first of these hydraulic systems is for providing the 180 rotation so that the feeding drum will start slowly, then accelerate its movement to rotate to the other side, then decelerate, and finally stop in the correct diametrically opposite position. This movement is provided by a hydraulic cylinder with a double running piston. A rope is attached at one end to the piston head. The piston is guided by suitably positioned rollers. The rope is attached at the other end to a side hook of the drum so that the movement of the hydraulic fluid under pressure alternately to one side or to the other side of the double effect piston brings about movement of the feeding drum. An electromagnetic brake or similar hydraulic, pneumatic, mechanical, electrical or electronic device may be positioned to assist in locating the drum in its exact position to enable the supplying of the tubes or bars to be drawn to their respective dies. The movements of the drum are synchronized with those of the drawing apparatus. The second of these hydraulic systems is for introducing the tubes or bars from the lower part of the feeding drum into the corresponding dies. The drum has at its end near the dies two opposite apertures of sufficient location, size and shape to permit the operation, including hoisting and pushing movements, of a set of tube or pipe grippers. The tube or pipe grippers are hydraulically or pneumatically controlled by appropriate pistons positioned and moving in respective hydraulic cylinders. The grippers grip the tubes or bars and introduce them into the respective dies. The grippers hold the tubes in the dies until the tubes are gripped by the grippers of the drawing carriage. The grippers are then released and hydraulically or pneumatically returned to their starting position.

In order that the present invention may be readily carried into effect, it will now be described with reference to the accompanying drawings, wherein:

FIG. 1 is a schematic diagram of an embodiment of the closed circuit hydraulic system of the present invention;

FIG. 2 is a cross-sectional view of one of the cylinders and its associated piston of FIG. 1;

FIG. 3 is a view, partly in section, of a piston guiding arrangement;

FIG. 4 is a cross-sectional view of an embodiment of the drawing apparatus of the present invention;

FIG. 5 is a cross-sectional view taken at another place of an embodiment of the drawing apparatus of the present invention;

FIG. 6 is a view, partly in section, of an embodiment of grippers for tubes, pipes, rods, bars and the like which may be utilized with the drawing apparatus of FIGS. 4 and 5;

FIG. 7 is a view, partly in section, of an embodiment of an arrangement for rotating the drum of the drawing apparatus of FIGS. 4 and 5; and

FIG. 8 is a side view, partly in section, of an embodiment of the drawing apparatus of the present invention.

The closed circuit hydraulic system of FIG. 1 includes a motor pumping unit 1, a fluid tank 2, an intercepting valve 3, a pressure gauge 4, a hydraulic distributor 5, a driving device 6 for said distributor having a speed reducer M, a pressure intensifier or pressure multiplier 7, a shock damper A, high pressure cylinders 8, 8, pistons 9, 9 rigidly aflixed, such as by welding or the like, to a drawing carriage 10 to form a strong drawing unit, a high pressure chamber C within the drawing carriage 10, hooks 11, 11 for carriage returning ropes 12, 12, and piston rings 13, 13 supporting the pistons 9, 9 for sliding movement within the high pressure cylinder 8, 8.

The electric motor and a winch operated by such motor for returning the drawing unit to its starting position is not shown, since it is well known.

In FIG. 2, the piston 9 moves within the high pressure cylinder 8. The piston ring 13 guides the piston 9 in its sliding movement and supports the piston against bending and twisting stresses within the high pressure cylinder 8.

FIG. 3 shows an arrangement for supporting and guiding the pistons 9 when they are outside the high pressure cylinders 8, during the drawing operation. A roller 14 is one of a plurality of rollers each shaped as illustrated to support the associated piston.

The drawing apparatus of FIG. 4 includes the rotatable feeding drum 16. The apparatus includes the pumping unit 1, the high pressure cylinders 8, the pistons 9, and the rotatable feeding drum 16. The drum 16 includes three tubular containers in its upper and lower parts, for drawing three tubes or bars at a time. The tubes or bars to be drawn are received from the supply of raw material. The rollers 18 rotate the drum 16.

In the drawing apparatus, as shown in FIG. 5, a longitudinal opening 23 is provided in the drawing bench. After being drawn, tubes or bars are discharged by gravity from the drawing bench through the opening 23 immediately after they are separated or removed from the respective dies and grippers 22. The apparatus includes the raw material supply 21, the forwarding track 20 for the feeding carriage 19 and for the supply of the raw material to the upper containers of the rotatable drum.

The grippers of the drawing carriage are hydraulically or pneumatically operated, as illustrated in FIG. 6. The grippers grip the ends of the tubes or bars projecting from the dies before they are drawn. The gripper arrangement includes a compensating fluid tank 32, a pumping unit P which is preferably driven by a small electric motor (not shown in the figures) synchronized with the movement of the drawing carriage, a hydraulic or pneumatic cylinder 24, a piston 25 and a piston stem 28. At the free end of the piston stem 28 a joint 30 supports three movably mounted grippers 29. Sliding rollers 31 facilitate the movement, in the gripping operation, of the grippers 29 within the conical mouth of the hydraulic cylinder 24. The gripper arrangement further includes a hydraulic distributor D, a fluid inlet 26 for the fluid under pressure for the movement of the grippers 29 in the gripping operation, and orifice 27 for compensating fluid behind the piston 25. Of course, the drawing carriage is provided with as many such hydraulic or pneumatic gripping systems as there are tubes or bars to be drawn at one time or in a single stroke of the drawing carriage.

The drum 16 is rotated by the drum rotating arrangement of FIG. 7. Rotation of the drum 16 supplies the tubes or bars to be drawn to the dies. The drum rotating arrangement includes drum moving rollers 18, a hydraulic or pneumatic cylinder 36, a double moving piston 37 which moves within said cylinder, supporting and guiding means 38 for said piston, a grooved roller 35 for rope 34 one end of which is attached to the head of the piston 37 and the other end of which is attached to a hook 33 on one side of the rotatable drum, a high pressure distributor 32 for controlling the rotation of said drum, and a valve V controlling fluid flow between the cylinder 36 and a fluid tank 40. The valve V permits the flow of tus for gripping and moving the tubes or bars to be drawn,

after the rotation of the drum, to the dies, in order to move said tubes into the dies and to hold said tubes in the dies until said tubes are gripped by the gripping arrangement of the drawing carriage. The drawing apparatus of FIG. 8 includes a fixed cylinder 42 having a piston 43, a track 49 along which a carriage 48 moves. The carriage 48 supports another cylinder 44 positioned at substantially right angles to the cylinder 42 and comprising a piston 45 having a stem 46 which supports at its upper end a particular type of gripper 47 of substantially V-type configuration. The gripper 47 is adapted to firmly grip the tubes or bars to be drawn and to move them, under the control of the piston 45 of the carriage 48, into the dies. The gripper 47 holds the tube in the die until the tube is gripped by the grippers of the drawing carriage and is then returned to its initial position by the piston 43 which moves the carriage 48, to which the piston 43 is attached.

The drum 16 is provided at its end near the die-holder with opposite cut out portions 41 to permit the tubes or bars to be drawn to be completely free of any obstacle in order to enable them to be moved by means of the system of FIGS. 7 and 8.

The foregoing specification embraces one of several possible embodiments of the invention. There are numerous possible variations, modifications and further improvements of a system based on the principle of the present invention of a hydraulic or pneumatic system for the operation of drawing benches for ferrous or nonferrous metal tubes, bars and/or the like in long pieces instead of the usual or conventional mechanical systems therefor. It is thus intended that such variations, modifications and improvements remain within the scope of the present invention.

What I claim is:

1. In a system for drawing tubes, pipes, rods, bars and the like, in combination,

a die for shaping a tube;

a pair of spaced cylinders fixed in position in operative proximity with said die;

a drawing carriage for drawing a tube through said die,

said drawing carriage having a high pressure chamber provided therein and a pair of spaced pistons of hollow configuration extending therefrom and opening into said high pressure chamber, each of said pistons being positioned substantially coaxially in a corresponding one of said cylinders for movement in an axial direction; and

a closed circuit hydraulic system for feeding hydraulic fluid under pressure to said cylinders and to said pressure chamber to move said drawing carriage via said hollow pistons and said high pressure chamber to apply full pressure to move said drawing carriage with drawing force to draw a tube through said die.

2. In a system for drawing tubes, pipes, rods, bars and the like, in combination,

a die for shaping a tube;

a pair of spaced cylinders fixed in position in operative proximity with said die;

a drawing carriage for drawing a tube through said die said drawing carriage having a high pressure chamber provided therein and a pair of spaced pistons of hollow configuration extending therefrom, fluid coupling means between each of said pistons and said high pressure chamber, each of said pistons being positioned substantially coaxially in a corresponding one of said cylinders for movement in an axial direction; and

a closed circuit hydraulic system for feeding hydraulic fluid under pressure to said cylinders and to said pressure chamber to move said drawing carriage via said hollow pistons and said high pressure chamber to apply full pressure to move said drawing carriage with drawing force to draw a tube through said die.

3. In a system for drawing tubes, pipes, rods, bars and the like, in combination,

a die for shaping a tube;

a pair of spaced cylinders fixed in position in operative proximity with said die;

a drawing carriage for drawing a tube through said die, said drawing carriage having a high pressure chamber provided therein and a pair of spaced pistons of hollow configuration extending therefrom, fluid coupling means between each of said pistons and said high pressure chamber, each of said pistons being positioned substantially coaxially in a corresponding one of said cylinders for movement in an axial direction, .a plurality of spaced coaxially mounted piston rings around each piston in each of said cylinders; and

a closed circuit hydraulic system for feeding hydraulic fluid under pressure to said cylinders and to said pressure chamber to move said drawing carriage via said hollow pistons and said high pressure chamber to apply full pressure to move said drawing carriage with drawing force to draw a tube through said die.

4. In a system for drawing tubes, pipes, rods, bars and the like, in combination,

a die for shaping a tube;

a pair of spaced cylinders fixed in position in operative proximity with said die;

a drawing carriage for drawing a tube through said die, said drawing carriage having a high pressure chamber provided therein and a pair of spaced pistons of hollow configuration extending therefrom, fluid coupling means between each of said pistons and said high pressure chamber, each of said pistons being positioned substantialy coaxially in a corresponding one of said cylinders for movement in an axial direction, a plurality of spaced coaxially mounted piston rings around each piston in each of said cylinders, each of said piston rings comprising an aluminum-bronze alloy; and

a closed circuit hydraulic system for feeding hydraulic fluid under pressure to said cylinders and to said pressure chamber to move said drawing carriage via said hollow pistons and said high pressure chamber to apply full pressure to move said drawing carriage with drawing force to draw a tube through said die.

5. In a system for drawing tubes, pipes, rods, bars and the like, in combination,

a die for shaping a tube;

a pair of spaced cylinders fixed in position in operative proximity with said die;

a drawing carriage for drawing a tube through said die,

said drawing carriage having a high pressure chamber provided therein and a pair of spaced pistons of hollow configuration extending therefrom, fluid coupling means between sach of said pistons and said high pressure chamber, each of said pistons being positioned substantialy coaxially in a corresponding one of said cylinders for movement in an axial direction, a plurality of spaced coaxially mounted piston rings around each piston in each of said cylinders; and

a closed circuit hydraulic system for feeding hydraulic fiuid under pressure to said cylinders and to said pressure chamber to move said drawing carriage via said hollow pistons and said high pressure chamber to apply full pressure to move said drawing carriage with drawing force to draw a tube through said die, said hydraulic system including pressure multiplier means for applying a greater than normal pressure to the drawing carriage at the initiation of movement of said drawing carriage.

6. In a system for drawing tubes, pipes, rods, bars and the like, in combination,

a die for shaping a tube; a pair of spaced cylinders fixed in position in operative a closed circuit hydraulic system for feeding hydraulic fluid under pressure to said cylinders and to said pressure chamber to move said drawing carriage via said hollow pistons and said high pressure chamber to apply full pressure to move said drawing carriage with drawing force to draw a tube through said die, said hydraulic system including shock damping means for absorbing shocks in said hydraulic system.

In a system for drawing tubes, pipes, rods, bars and the like, in combination,

die for shaping a tube;

a pair of spaced cylinders fixed in position in operative proximity with said die;

drawing carriage for drawing a tube through said die, said drawing carriage having a high pressure chamber provided therein and a pair of spaced pistons of hollow configuration extending therefrom and opening into said high pressure chamber, each of said pistons being positioned substantially coaxially in a corresponding one of said cylinders for movement in an axial direction;

a closed circuit hydraulic system for feeding hydraulic fluid under pressure to said cylinders and to said pressure chamber to move said drawing carriage via said hollow pistons and said high pressure chamber .8 p I to apply full pressure to move said drawing carriage with drawing force to draw a tube through said die; and

guide means fixed in position for guiding said pistons in their movement outside said cylinders.

In a system for drawing tubes, pipes, rods, bars and the like, in combination,

a die for shaping a tube; a pair of spaced cylinders fixed in position in operative proximity with said die;

drawing carriage for drawing a tube through said die, said drawing carriage having a high pressure chamber provided therein and a pair of spaced pistons of hollow configuration extending therefrom and opening into said high pressure chamber, each of said pistons being positioned substantially coaxialy in a corresponding one of said cylinders for movement in an axial direction;

a closed circuit hydraulic system for feeding hydraulic fluid under pressure to said cylinders and to said pressure chamber to move said drawing carriage via said hollow pistons and said high pressure chamber to apply full pressure to move said drawing carriage with drawing force to draw a tube through said die; and

guide means fixed in position for guiding said pistons in their movement outside said cylinders, said guide means comprising rollers each having a groove formed in the periphery thereof and supporting said piston in said groove.

References Cited by the Examiner UNITED STATES PATENTS 2,472,231 6/ 1949 Rodder 205-24 2,873,849 2/1959 Lombard 2053 3,078,984 2/1963 Baker 20524 3,108,503 10/1963 Murek 78-42 FOREIGN PATENTS 782,636 9/1957 Great Britain.

CHARLES W. LANHAM, Primary Examiner. 

1. IN A SYSTEM FOR DRAWING TUBES, PIPES, RODS, BARS AND THE LIKE IN COMBINATION, A DIE FOR SHAPING A TUBE; A PAIR OF SPACED CYLINDERS FIXED IN POSITION IN OPERATIVE PROXIMITY WITH SAID DIE; A DRAWING CARRIAGE FOR DRAWING A TUBE THROUGH SAID DIE, SAID DRAWING CARRIAGE HAVING A HIGH PRESSURE CHAMBER PROVIDED THEREIN AND A PAIR OF SPACED PISTONS OF HOLLOW CONFIGURATION EXTENDING THEREFROM AND OPENING INTO SAID HIGH PRESSURE CHAMBER, EACH OF SAID PISTONS BEING POSITIONED SUBSTANTIALLY COAXIALLY IN A CORRESPONDING ONE OF SAID CYLINDERS FOR MOVEMENT IN AN AXIAL DIRECTION; AND A CLOSED CIRCUIT HYDRAULIC SYSTEM FOR FEEDING HYDRAULIC FLUID UNDER PRESSURE TO SAID CYLINDERS AND TO SAID PRESSURE CHAMBER TO MOVE SAID DRAWING CARRIAGE VIA SAID HOLLOW PISTONS AND SAID HIGH PRESSURE CHAMBER TO APPLY FULL PRESSURE TO MOVE SAID DRAWING CARRIAGE WITH DRAWING FORCE TO DRAW A TUBE THROUGH SAID DIE. 